At Steam Dev Days, a Seattle game developer conference hosted by Valve Software, the company showed off its own virtual reality prototype. It was built as an example of what VR could become in five to ten years, and it seemed to convince everyone who used it. Its key difference from Rift is that it requires users to be in a specially decorated room dotted with blackand-white markers. Luckily for those who don’t enjoy decorating, Valve has no intention of releasing its prototype, despite its hardware ambitions with Steam Machines and controllers. This hasn’t stopped Jonathan Blow working with Valve to make his next game, The Witness, work with the system, however.